FeCl3 Solution Research Articles

Functional Design Of Peroral Delivery Systems Based On Polymethylsesquoxane Hydrogels For The Therapy Of Iron Deficiency Anemia

Anemia is a prevalent circulatory system illness that is severely harmful to patients. The development of novel oral delivery systems for iron compounds with enhanced biopharmaceutical properties is vital considering the severe side effects associated with oral medication use. We believe incorporating iron compounds to polymethylsilsesquioxane hydrogels is a promising approach. According to previously published materials, such a system should have great biocompatibility and a capacity for iron compounds, and it may be able to release contents into the intestine. This study investigated polymethysilsesquioxane hydrogels with varying silicate unit concentrations. Potential iron-containing medicines were iron(III) chloride (FeCl3∙6H2O)) and iron(II) D-gluconate. All hydrogels were found to have nearly 100% sorption activity for a saturated solution of FeCl3∙6H2O (0.27 M) during the experiment, but only around 30% sorption capacity was found for a saturated solution of D-gluconate (0.24 M). A specific field of study was the distribution of iron atoms within hydrogels. It has been established that the largest regions devoid of iron atoms are observed in a hydrogel with a maximum quantity of inorganic units. The outcomes provide opportunities for the precise engineering of polymer matrix structures for iron compound delivery.

Enhanced phosphorus adsorption using modified drinking water treatment residues: A comparative analysis of powder and alginate bead forms

This study provides an analysis of the phosphorus adsorption efficacy of three modified drinking water treatment residues (MDWTRs): MDWTR-P (powdered form), MDWTR-D2, and MDWTR-D5 (alginate bead-entrapped forms with bead diameters of 2 mm and 5 mm, respectively). The preparation process involved washing and drying the drinking water treatment residue, followed by grinding and sieving to achieve particle sizes below 90 μm. The residue was then incinerated at 600 °C in oxygen-limited conditions. Subsequently, the MDWTR was formulated into alginate beads by mixing with sodium alginate and FeCl3 solutions, resulting in spherical particles of specified diameters. The evaluation of surface area, pore volume, pore size, and CHN concentration revealed that MDWTR-D5 possesses the largest surface area (284.7 m2 g−1) and highest micropore volume (0.04 cm3 g−1), indicating a greater capacity for adsorption. SEM-EDS analysis demonstrated significant compositional changes post-treatment, particularly elevated phosphorus levels, confirming effective adsorption. Metal content analysis indicated high aluminum levels in MDWTR-P and increased iron content in MDWTR-D5. Toxicity Characteristic Leaching Procedure (TCLP) and in vitro bioaccessibility (IVBA) tests confirmed the non-hazardous nature of all MDWTRs, ensuring their safety for environmental applications. Kinetic analyses using pseudo-first-order, pseudo-second-order, and intraparticle diffusion models highlighted the superior performance of MDWTR-D5, with the highest equilibrium adsorption capacity and initial adsorption rate across all tested concentrations, suggesting both high efficiency and rapid adsorption potential. Further validation using Langmuir and Freundlich isotherms revealed MDWTR-D5's highest monolayer adsorption capacity (22.88 mg g−1) and Freundlich adsorption capacity parameter (6.97 mg g−1). Statistical analysis via one-way ANOVA confirmed significant differences in phosphorus concentrations among the MDWTRs samples (p-value <0.001), consistently underscoring MDWTR-D5's superior adsorption performance. These findings highlight MDWTR-D5's potential as an effective adsorbent for phosphorus removal in wastewater treatment, emphasizing its applicability in environmental remediation strategies.

Sustainable Removal of Cr(VI) from Wastewater Using Green Composites of Zero-Valent Iron and Natural Clays

Composites for efficient removal of hexavalent chromium Cr(VI) from industrial wastewater were obtained by deposition of nano-zero-valent iron (nZVI), synthesized by environmentally friendly synthesis using oak leaf extract, on inexpensive, natural, readily available and cheap natural raw materials, sepiolite (SEP) or kaolinite/illite (KUb) clay, as support. nZVI particles were deposited from the FeCl3 solution of different concentrations, with the same volume ratio extract/FeCl3 solution (3:1), and with different masses of SEP or KUb. Physico–chemical characterization (SEM/EDS, FTIR, BET, determination of point of zero charge) of the composites and nZVI was performed. The results of SEM and BET analyses suggested more homogeneous deposition of nZVI onto SEP than onto KUb, which ensures greater availability of the nZVI surface for Cr(VI) anions. Therefore, the higher Cr(VI) removal at all investigated initial pH values (pHi) of the solution (3, 4 and 5) was achieved with the SEP composites. The adsorption results indicated that the elimination of Cr(VI) was achieved via the combined effect of reduction and adsorption. The removal of total chromium at pHi = 3 was approximately the same as that of Cr(VI) removal for the KUb composites, but lower for the SEP composites, indicating lower removal of Cr(III) compared to the reduced Cr(VI). The SEP/nZVI composite with the highest removal efficiency was applied for Cr(VI) removal from real wastewater at pHi = 3 and pHi = 5. The results demonstrated the high Cr(VI) removal capacity, validated the assumption that a good dispersion of nZVI particles is beneficial for Cr(VI) removal and showed that the produced green composites can be efficient materials for the removal of Cr(VI) from wastewater.

Spirulina biomass loaded with iron nanoparticles: A novel biofertilizer for the growth and enrichment of iron content in rice plants

The current investigation was focused to develop a nano-iron-based phycofertilizer to enhance crop quality in an environment-friendly manner. Biosynthesis of nano-iron occurred when Spirulina biomass was exposed to a 0.05M FeCl3 solution for 48h at pH 5.5 in the dark, resulting in the synthesis of spindle-shaped nano-iron both inside and outside the cells. The particles' sizes were 24.77 ± 5.264 nm as observed in transmission electron microscopy. Further characterizations were carried out using energy dispersive X-ray spectroscopy (EDX), and dynamic light scattering (DLS). The performance of various fertilizers, including those derived from phycosynthesized nano iron (INP), dried Spirulina biomass (SB), and nano-iron loaded Spirulina biomass i.e., nano-phycho-fertilizer (NPF) was compared against conventional NPK fertilizer. The results from field applications indicated significant improvements in rice, with NPF outshining the rest. Notably, NPF demonstrated a remarkable 37.6% increase in shoot length, a 47% boost in crop productivity, and a 15% rise in grain weight of rice compared to NPK. Both unpolished and polished grains of NPF-treated plants contained higher iron contents (44% and 28%) than the NPK-treated plants. Furthermore, the cost-effectiveness analysis underscored the superiority of NPF over conventional fertilizer, representing it as a highly effective and eco-friendly nano-iron-based phycofertilizer.

Lithium extraction from a clay-type lithium ore using a mixed solution of sulfuric acid and ferric chloride

The demand for lithium resources continues to grow owing to the extensive application of lithium-ion batteries in the clean energy industry, and in consequence the development of lithium extraction technologies is significant. In this study, the mixed solution of H2SO4 and FeCl3 was found to have a synergistic effect on the lithium extraction from a clay lithium ore. Upon calcination at 600 °C for 60 min, followed by leaching with a mixture of 10.5 w% H2SO4 and 2 w% FeCl3 at a liquid-to-solid ratio of 5 mL/g for 90 min at 80 °C, a lithium leaching efficiency of 96.18 % was obtained, better than using individual H2SO4 and FeCl3 at higher concentrations. The TG-DTG-DSC, FTIR, BET and XRD results showed that with the increase of calcination temperature the structures of partial minerals such as kaolinite and cookeite became collapsed, amorphous, unstable and activated, which favored for the release of lithium. With the further increase of calcination temperature, the mineral structure continued to collapse and tends to be stable, making the interlayer lithium tightly fixed and difficult to be released. The XRD and SEM results indicated that the lithium extraction is an ion exchange process rather than mineral dissolution. The synergistic effect of H2SO4 and FeCl3 on the lithium extraction was attributed to the fact that the entry of Fe3+ into the interlayer of the layered structure of clay minerals not only released Li+, but also increased the interlayer spacing, conducive to the access of H+ to the interlayer, and consequently facilitated the ion exchange of H+ and Li+.

Preparation and application of wood-supported piezocatalyst with high efficiency and stability via partial hydrolysis of wood cellulose and hemicellulose with Lewis acid

The conveniently recoverable piezocatalyst with self-floating and stable performance has drawn wide attention. Herein, MoS2 was anchored on 1-cm-square eucalyptus wood blocks via a facile hydrothermal/solvothermal process to fabricate two floating piezocatalysts, i.e., MoS2/unpretreated wood (MUW) and MoS2/pretreated wood (MPW). FeCl3 solution was used as a Lewis acid to pretreat the wood through partial hydrolyzing cellulose and hemicellulose for an purpose to creat rich micropores for MoS2 loading in the wood and to form MoFe heterojunction. The piezocatalytic properties and performance of the prepared wood were systematically studied. The scanning electron microscopy confirms MoS2 was anchored on wood surface. The macroscopic photos show that MoS2 penetrated through the MPW interior whereas it was only loaded on the wood surface layer. The X-ray photoelectron spectroscopy reveals the shift of Mo 3d and S 2p, verifying the heterojunction formation of MPW. The Fourier transform infrared spectra prove the partial hydrolysis of wood matrix. In comparison to MUW, MPW had excellent piezocatalytic property, wide pH adaptability, convenient recyclability and high stability. Sildenafil and Cr6+ ions could be completely removed in 20 and 15 min, respectively, by MPW. Contrastly, the removal efficiency of sildenafil and Cr6+ by MUW was 78.6 % and 68.3 % in 20 and 15 min, respectively. After five cycles of use, the removal ratio of sildenafil was 62.4 % by MUW and 90.5 % by MPW in 20 min. The mineralization efficiency of sildenafil reached 99.2 % in 30 min by MPW, and various types of N/S-containing intermediates were effectively degraded. The electron spin resonance characterization and active species scavenging experiments displayed that e− and •O2− were major active species responsible for Cr6+ piezoreduction by MUW and MPW, while •O2− and •OH were the dominant species accounting for sildenafil degradation by MUW and MPW, respectively. And •OH was not generated in the MUW piezocatalysis process. MPW had higher piezoelectric current and lower resistance at the electron transfer interface than MUW. Conclusively, this study paves a new pathway for preparing new floating piezocatalysts with easy recyclability and high stability from biomass for wastewater treatment.

Carbon quantum dots-loaded fluorescent hydrogel for Fe3+ ions detection

ABSTRACT We synthesised a polyacrylamide (PAA) hydrogel filled with fluorescent carbon quantum dots (CQDs) for environmental sensing application. The obtained PAA@CQDs composite was characterised using scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, photoluminescence (PL) spectroscopy, time correlated single photon counting and UV-visible spectroscopy. In the PAA@CQDs composite, CQDs were shown to retain their high PL properties. Being immersed into FeCl3 solutions, PAA@CQDs samples demonstrated intensive PL quenching because of Fe3+ ions absorption. The limit of the Fe3+ ions detection was determined to be 0.124 μM. We showed the formation of non-PL complex between CQDs and Fe3+ ions, ensuring static mechanism of the PAA@CQDs PL quenching.

Polypyrrole-mediated construction of superhydrophobic photo/electro thermal composite fabric for efficient crude oil dehydration and recovery

During crude oil extraction, transportation, and oil spill recovery, rapid and effective removal of water from crude oil is a great challenge. Super-hydrophobic functional membranes with electrothermal/photothermal effects are considered to be an effective method. However, simply polymerizing photothermal/electrothermal nanomaterials on the membrane surface will lead to unstable thermal effects and easy shedding. Therefore, in this study we propose the synthesis of a novel superhydrophobic electrothermal/photothermal Nylon fabric (PSPPNF) by an innovative in situ polymerization method of Pyrrole (Py), to realize efficient viscosity reduction and dehydration of crude oil. In particular, by controlling FeCl3 solution from solid (−18 °C) to liquid state (0 °C), Py was polymerized on the fabric surface by slow oxidative process, which can effectively solve the problem of pore blocks to obtain a stable-conductive layer on the NF surface. The PSPPNF surface temperature can reach 80 °C under 1 kW m−2 sunlight intensity or by inputting 30 V, which brings a separation efficiency of 97 % for high-viscous crude oil/water mixture. We systematically analyzed the effects of PSPPNF with different pore sizes and oils with different viscosities on the separation flux, as well as the effects of the thermal properties of the membranes under different illumination conditions and voltages on crude oil permeation. Additionally, the PSPPNF combined with the roller can realize all-weather available crude oil spill recovery under solar and electrical energy. This work provides new insights into membrane materials that can realize the efficient dehydration and recovery of crude oil for day-night alternation and complex environments.

Laser ablation and chemical vapor deposition to prepare a nanostructured PPy layer on the Ti surface

Abstract The deposition of polypyrrole (PPy) on a Ti surface is commonly employed to enhance the material’s properties for different applications such as supercapacitors, biomedicine, and corrosion resistance. Instead of complex or costly polymerization procedures for the PPy synthesis on the Ti metal surface, we utilized the effect of a simple and inexpensive laser ablation of the Ti surface in the open-air environment to prepare a hydrophilic TiO2 surface. In this condition, a thin PPy layer with remarkable nanostructures such as nanorings (∼80 nm) and nanotubes (∼245 nm) was deposited on a selective and desired pattern of ablated Ti areas through the chemical vapor deposition process using ferric chloride (FeCl3) solution as a pyrrole oxidizer. Raman and X-ray photoelectron spectroscopy (XPS) analyses confirmed the PPy formation on the Ti surface. The creation of these nanostructures was due to the micro/nanomorphology of the ablated Ti substrate. Water contact angle (WCA) measurements indicated the hydrophobic behavior of the PPy/Ti surface by the aging effect after 24 weeks with the change of WCA from 20° to 116°. The change in the surface chemical composition upon adsorption of airborne organic compounds with the long-term storage of PPy/Ti surface in air was studied by the XPS test.

Enhancement of visible-light photocatalysis of TiO2 via nanocomposite incorporating with Fe(III) species

This paper introduces a novel approach for the synthesis of photocatalytic nanocomposites via a fast reaction occurring at ambient conditions between the strong base NaOH and FeCl3 solution to obtain a fresh precipitate of Fe(OH)3 in the presence of TiO2 nanoparticles. FE-SEM analysis revealed a restructured state of TiO2 particles on the surface of colloidal Fe(OH)3. Solid-phase studies, including XRD and FT-IR, indicated a phase transformation from Fe(OH)3 to γ-Fe2O3 during the formation of the nanocomposite. UV–Vis diffuse reflectance measurements confirmed a significant reduction in the band gap of the synthesized composite, indicating its potentials as a photocatalyst under visible light irradiation. Another advantage of this composite type is its rapid sedimentation ability within minutes, facilitating post-processes such as phase separation and catalyst reuse on a large scale, which are challenging in the case of TiO2 nanoparticles. Inducing photocatalysis under visible light, the efficiency in degrading persistent colorants was demonstrated through a case study of indigo carmine (IC), which exhibited a threefold improvement in degradation efficiency for the case of the nanocomposite compared to the original TiO2. Indeed, the IC degradation process was studied in consideration of various factors such as Fe/Ti ratio in the catalyst, illumination time, colorant concentration, catalyst dosage, and pH of the environment. Additionally, mineralization studies confirmed the oxidation of IC to CO2 rather than the formation of potentially toxic intermediates. Furthermore, the stability of the catalyst was examined through six cycles of reuse.

Effect of multiple laser remelting on microstructure and corrosion resistance of Fe0.5CoCrNi1.5Nb0.68Mo0.3 high entropy alloy coatings

High entropy alloy (HEA) coatings of Fe0.5CoCrNi1.5Nb0.68Mo0.3 was prepared on 304 stainless steel using laser cladding and subsequently remelted multiple times. The effects of multiple thermal cycles on the phase composition, grain size, microstructure evolution, and corrosion resistance of the coatings are thoroughly investigated. The original coating consisted of face-centered cubic (FCC), Laves, and NbC phases, and the phase composition does not change obviously, but the distribution and microstructure of the phase change significantly after multiple remelting. As the number of remelting times increased, the bar-like eutectic structure decreased while the lamellar eutectic structure became more prominent. Laser remelting induced dynamic recrystallization in the coating, resulting in a transformation from columnar grains to equiaxed grains, and then back to columnar grains. The grain size also changes significantly with different remelting times. Potentiodynamic polarization and electrochemical impact spectroscopy measurements were conducted in a 3.5 wt% NaCl solution to evaluate the corrosion resistance of the coating. The results revealed both the original coating and the once-remelted coating exhibited lower corrosion current density and higher corrosion potential, but the latter had a higher Faraday impedance. Additionally, immersion tests were performed in 10 wt% FeCl3 solution, which demonstrated that the once-remelted coating displayed fine and uniform corrosion pits with shallow depth. This study provides theoretical support for the regulation of microstructure and the optimization of coating performance. Furthermore, the microstructure evolution law discovered in this research is also applicable to additive manufacturing.

Preparation of mussel-inspired adhesion nanocapsules and their application on cotton fabrics

In this study, a hyperbranched polymer (HBP) with a hydrophobic backbone and hydrophilic adhesive catechol side chains was synthesized through the Michael addition reaction between multi-vinyl monomers with dopamine. Underwater adhesion experiments demonstrated that HBP had rapidly strong adhesion. Using HBP as the wall material and lavender essential oil (LO) as the core material, catechol-hyperbranched nanocapsules (CHNPs) with good adhesion and acidic responsive properties were prepared by solvent evaporation method. Subsequently, ACFs with good wash resistance were prepared by impregnation and further introduction of Fe3+. After 25 washing cycles, the retention rate of LO in CF treated solely with CHNPs solution (CHNPs@CF) was only 9.7 %, whereas the retention rate increased to 17.8 % for CHNPs@CF treated with FeCl3 solution (Fe3+/CHNPs@CF). The persistent adhesion of CHNPs on cotton fabrics (CF) is achieved by hydrogen bonding and Fe3+-catechol coordination bonding. These results confirm the significant potential of CHNPs in aromatic textile applications and it is expected to promote the diversified development of functional textiles.

Highly sensitive and flexible ammonia sensor based on PEDOT:PSS doped with Lewis acid for wireless food monitoring

Ammonia serves as a crucial indicator of food spoilage, but current sensors lack sufficient sensitivity, stability, selectivity, and automation for practical on-site and real-time monitoring. A highly sensitive and flexible ammonia sensor based on PEDOT:PSS doped with Lewis acid (FeCl3 solution) for wireless food monitoring is proposed in this study to solve the above limitations. The intercalation effect caused by the diffusion of Fe3+ and hydrolyzed H+ in the film coordinating with SO3− groups present in PSS chains leads to an increased distance between adjacent PEDOT-rich domains. It enhances ammonia sensitivity by providing additional ionic carriers and carrier transport paths within the PEDOT:PSS molecule. The results demonstrated a significant enhancement in the sensitivity of PEDOT:PSS sensor doped with FeCl3, exhibiting a response value of about 25 % at 25 ℃ for 1 ppm NH3, with an impressive detection limit of 0.23 ppm and quantification limit of 0.78 ppm (1–400 ppm). Moreover, it showcases acceptable repeatability both at 1 ppm (RSD = 4.30 %) and 100 ppm ammonia (RSD = 3.61 %), along with the notable selectivity and long-term stability. XPS, Raman analysis, and the density function theory (DFT) calculations further elucidated the sensing mechanism of the sensor towards ammonia. Additionally, a portable wireless detection device was designed, which was equipped with the Bluetooth communication and the micro-controller system to detect the decay process of fresh shrimp, realizing wirelessly real-time monitoring of food freshness through a smart phone. It’s worth noting that the innovative sensing technology holds great promise for food quality monitoring.

Titania-zeolite composite for tetracycline photocatalytic degradation under visible light: A comparison between doping and ion exchange

In this study, TiO2 supported over embryonic Beta zeolite (BEA) was prepared for the photocatalytic degradation of Tetracycline (TC) antibiotic under visible light. The immobilization of sol-gel TiO2 over the zeolite increased its surface area from 33 (m2/g) to 226 (m2/g) and enhanced its adsorption efficiency from 8 % to 18 %. In order to expand the photocatalytic activity of TiO2 towards the visible light region (i.e. λ > 380 nm), two different metal sensitization techniques with Iron ions from aqueous solution of FeCl3 were explored. In the ion-exchange method, the substitutional cations within the TiO2/BEA structure were exchanged with Fe3+. Whereas, in the doping technique, solgel TiO2 was doped with Fe3+ during its synthesis and before its immobilization over Zeolite. Four different samples with 20, 40, 60, and 100 % w/w of TiO2/BEA ratio were prepared. After testing the various ion-exchanged photocatalysts under blue and white lights, only Fe–60%TiO2/BEA showed better activity compared to pure TiO2 under white light at TC initial concentration, Co = 20 ppm. For the doped immobilized Titania with 60 wt% TiO2/BEA, three different doped photocatalysts were prepared with 3 %, 7 %, and 10 % per mole Fe/TiO2. All the Fe-doped TiO2/BEA photocatalysts showed better activity compared to pure TiO2 under white light. Under solar irradiations, the 3 % Fe-doped TiO2/BEA was able to degrade all TC within 120 min, while Fe–60%TiO2/BEA needed 200 min, and TiO2 needed more than 300 min. This enhanced performance was a result of both increased surface area due to immobilization over BEA as well as iron doping by Fe3+ that simultaneously increased the visible light absorption of TiO2 and minimized the charge carrier recombination effect.

A gelatin-based ionic conductor with a dense/loose alternating network enabled by surface active cellulose

Although conductive and stretchable ionic conductors are increasingly prepared for flexible sensing applications, such as health monitoring, tissue engineering, and electronic skin, achieving a balance between remarkable mechanical properties and high sensing sensitivity remains a significant challenge. In this work, a dense/loose alternating network was meticulously constructed through a pre-assembly process in sodium citrate solution and a subsequent re-assembly in FeCl3 solution. This approach ensured the robustness of the network structure and facilitated ion migration. Within the network, a gelatin network cross-linked via covalently and hydrogen bonds was significantly enhanced by a synergy of micro-enhancement and dynamic bidirectional crosslinking containing hydrogen bonds, imine bonds, and Fe coordinate bonds enabled by surface active cellulose. Benefiting from the dense network, the obtained composite hydrogels delivered a strong tensile strength (496.3 kPa), outstanding elastic modulus (917.6 kPa), and an excellent energy dissipation rate (55.6 %) at 80 % of strain. The loose polymer network can also endow Fe3+/Cl− ions with sensitive mobility, leading to an ultra-high sensing sensitivity (maximum GF: 20.06). These exceptional properties enable the ionic conductor to accurately detect a wide range of motions and pressures without being affected by environmental noise. With attributes such as reusability, biodegradability, strength, and sensitivity, this ionic conductor emerges as a reliable soft material with promising applications in the field of healthcare monitoring, wearable strain sensor sensors, and writing anti-counterfeiting materials.

Corrosion Study on Duplex Stainless Steel UNS S31803 Subjected to Solutions Containing Chloride Ions.

In the present work, the influence of a corrosive environment and temperature on the corrosion resistance properties of duplex stainless steel S31803 was evaluated. The corrosive process was carried out using solutions of 1.5% HCl (m/m) and 6% FeCl3 (m/m), at temperatures of 25 and 50 °C. The microstructure of UNS S31803 duplex stainless steel is composed of two phases, ferrite and austenite, oriented in the rolling direction, containing a ferrite percentage of 46.2% in the rolling direction and 56.1% in the normal direction. Samples, when subjected to corrosive media and temperature, tend to decrease their mechanical property values. It was observed, in both corrosive media, that with increasing test temperature, there is an increase in the corrosion rate, both uniform and pitting. The sample in HCl solution obtained a uniform corrosion rate of 0.85% at 25 °C and 0.92% at 50 °C and pitting rates of 0.77% and 1.47% at the same temperatures, respectively. When tested in FeCl3 solution, it obtained uniform corrosion of 0.0006% and 0.93% and pitting of 0.53% and 18.5%, at the same temperatures. A reduction in dissolution potentials is also noted, thus characterizing greater corrosion in the samples with increasing temperature.

Investigations on corrosion behavior of 316LN and 316L austenitic stainless steel under corrosion-deformation interactions

PurposeThis paper aims to explore the influence of corrosion-deformation interactions (CDI) on the corrosion behavior and mechanisms of 316LN under applied tensile stresses.Design/methodology/approachCorrosion of metals would be aggravated by CDI under applied stress. Notably, the presence of nitrogen in 316LN austenitic stainless steel (SS) would enhance the corrosion resistance compared to the nitrogen-absent 316L SS. To clarify the CDI behaviors, electrochemical corrosion experiments were performed on 316LN specimens under different applied stress levels. Complementary analyses, including three-dimensional morphological examinations by KH-7700 digital microscope and scanning electron microscopy coupled with energy dispersive spectroscopy, were conducted to investigate the macroscopic and microscopic corrosion morphology and to characterize the composition of corrosion products within pits. Furthermore, ion chromatography was used to analyze the solution composition variations after immersion corrosion tests of 316LN in a 6 wt.% FeCl3 solution compared to original FeCl3 solution. Electrochemical experiment results revealed the linear decrease in free corrosion potential with increasing applied stress. Electrochemical impedance spectroscopy results indicated that high tensile stress level damaged the integrity of passivation film, as evidenced by the remarkable reduction in electrochemical impedance. Ion chromatography analyses proved the concentrations increase of NO3− and NH4+ ion concentrations in the corrosion media after corrosion tests.FindingsThe enhanced corrosion resistance of 316LN SS is attributable to the presence of nitrogen.Research limitations/implicationsThe scope of this study is confined to the influence of tensile stress on the electrochemical corrosion of 316LN at ambient temperatures; it does not encompass the potential effects of elevated temperatures or compressive stress.Practical implicationsThe resistance to stress electrochemical corrosion in SS may be enhanced through nitrogen alloying.Originality/valueThis paper presents a systematic investigation into the stress electrochemical corrosion of 316LN, marking the inaugural study of its impact on corrosion behaviors and underlying mechanisms.

Evidence of Sharp Transitions between Octahedral and Capped Trigonal Prism States of the Solvation Shell of the Aqueous Fe3+ Ion.

The structure of the solvation shell of the aqueous Fe3+ ion has been a subject of controversy due to discrepancies between experiments and different levels of theory. We address this issue by performing simulations for a wide range of ion concentrations, using various potential energy functions, supplemented by density functional theory calculations of selected configurations. The solvation shell undergoes abrupt transitions between two states: a hexacoordinated octahedral (OH) state and a capped trigonal prism (CTP) state with 7-fold coordination. The lifetime of these states is dependent on concentration. In dilute FeCl3 solutions, the lifetimes of both are similar (≈1 ns). However, the lifetime of the OH state increases with ion concentration, while that of the CTP state decreases slightly. When a uniform negative background charge is used instead of explicit counterions, the lifetime of the OH state is greatly overestimated. These findings underscore the need for further experimental measurements and higher-level simulations.

Effects of TiN content and heat treatment on microstructural changes, mechanical strength, and corrosion resistance in selective laser melting of TiN/AISI 420 composites

This study investigates the influence of Titanium Nitride (TiN) concentration variations and heat treatment on the microstructure, strength, and corrosion resistance of TiN/AISI 420 composites fabricated via selective laser melting (SLM). Results demonstrate that the addition of TiN particles (2 μm in size) at 0.5, 1, and 2 wt percent (wt. %) to the AISI 420 alloy enhances the toughness modulus of SLM TiN/AISI 420 to 37.0 ± 1.5 J/m3, 42.2 ± 0.4 J/m3, and 36.2 ± 0.7 J/m3, respectively, surpassing the SLM AISI 420's toughness of 21.3 ± 0.6 J/m3. Moreover, a positive relationship between TiN content and corrosion resistance is observed, with 2 wt % TiN/AISI 420 composites exhibiting the highest resistance at 105.6 ± 2.5 mm/year in a 6 wt % FeCl3 solution. Following heat treatment, a reduction in hardness is noted due to decreased surface residual stress and increased retained austenite. However, treated composites demonstrate improved mechanical and corrosion resistances. Particularly noteworthy is the highest toughness of 118.0 ± 1.3 J/m3 observed in 1 wt % TiN composites and a corrosion rate of 104.7 ± 2.7 mm/year in 2 wt % TiN composites. The homogeneous dispersion of TiN particles and the phenomenon of transformation-induced plasticity significantly enhance toughness, while increased levels of retained austenite contribute to improved corrosion resistance. This work underscores the potential of advanced manufacturing techniques in developing composite materials with diverse applications, such as robotic mold inserts. It emphasizes the pivotal role of composite formulation and post-processing in augmenting material performance.

FeCl3-Induced Oxidation of POME for Efficient Treatment: An Experimental Study

POME is a biomass waste product from cooking oil in the food industry which requires well treatment before discharge to the main stream. It becomes problematic cause POME contains a lot of organic compounds, suspended solids, lipids, and others which is hazard. Proper treatment is necessary in order to avoid adverse effects on the aquatic and fresh water quality. As that concerned, FeCl3 was introduced to initiate the oxidation reaction and indirectly to degrade the organic compounds in the POME. Throughout the experiment, 0.005 M of FeCl3 solution was mixed into each untreated POME. Besides POME, Glucose and lignin has been used for comparative study. Since POME is biomass waste, UV-Vis Spectroscopy instrumentation is the best to characterize the degradation behavior of organic compounds contained in POME, as well as in glucose and lignin. Based on Lamda, λ Max, the absorbance value as the indicator to measure the degradation level. The experiment done in room temperature (±25 °C) and catalyst optimization was done by Cyclic Voltammetry, CV with potential window from -0.1 to 1.5 V and for UV-Vis spectroscopy, the wavelength(nm) range between 200-600 nm was set throughout the analysis.